shut off engine while filling tank

just learned something interesting today. my 99 1500 w/5.3L engines "service engine soon" light came on a week ago. i brought it in today and the shop could not find anything specific wrong,they reset it so the light went off.

then they told me this: do not fill up your truck with engine running. the computer runs random checks,and will notice the gas cap isnt on,therefore setting off the light. also it takes 2 consequetive trips with a gas tank between 1/4 and 3/4 full,from cold start to hot,around ten miles in length,to remedy the light on its own. i dont know why it never reset itself,but it did not. a loose gas cap will set off the sensor for the "ses" light also.

cost me 42 bucks to learn this today:rolleyes:

FYI..

brad

found that out w/my 98 venture

just learned something interesting today. my 99 1500 w/5.3L engines "service engine soon" light came on a week ago. i brought it in today and the shop could not find anything specific wrong,they reset it so the light went off.

then they told me this: do not fill up your truck with engine running. the computer runs random checks,and will notice the gas cap isnt on,therefore setting off the light. also it takes 2 consequetive trips with a gas tank between 1/4 and 3/4 full,from cold start to hot,around ten miles in length,to remedy the light on its own. i dont know why it never reset itself,but it did not. a loose gas cap will set off the sensor for the "ses" light also.

cost me 42 bucks to learn this today:rolleyes:

FYI..

brad

You shouldn't leave your vehicle running when you fill your tank anyway..it's a fire hazard..thats what all those warning signs are on the gas pumps :loser:

What happens is the PCM runs a vacum test on the gas tank to see if there are any leaks...if the tank loses vacum, it will set the SES light.

No one said education was cheap but damn that sucks.